The invention is a solenoid valve mounted within the bore of a ferromagnetic journal for operating a clutch which drives an engine cooling fan.
U.S. Pat. No. 6,092,638 to Vatsaas issued Jul. 25, 2000 discloses a spineless rotational control apparatus otherwise known as a clutch. FIG. 1 of the ""638 patent has been designated as prior art in the drawings of the instant invention.
FIG. 1 is a cross-sectional view of the prior art illustrating a clutch operated by the application of air pressure through a seal. The prior art clutch, journal and cartridge are generally indicated with reference numeral 100. Journal 101 includes a cartridge 102. Belt drive sheave 103 is rotatably driven by belts not shown. Belt driven sheave 103 rotates with respect to journal 101 as bearings 116 are interposed between the sheave and the journal 101.
Cartridge 102 includes a seal 117. Seal 117 engages coupling 114 for the transmission of air pressure which is available from an air supply source 106. Cap 104 is secured to sheave 103 by a snap ring 115. Cap 104 rotates in unison with sheave 103. When air is supplied to the coupling 114 it is admitted into the volume as indicated by reference numeral 111. When air pressure of sufficient magnitude exists in volume 111 friction surface 110 which is rotating in unison with sheave 103 disengages friction surface 109 which causes a fan (not shown) to stop rotating.
Application of air pressure to volume 11 causes clutch 105 to move leftwardly when viewing FIG. 1 of the instant application. Reference numeral 112 is an arrow indicating movement of the clutch plate 105. Lugs 108 are mounts for a fan blade. Journal 101 is typically affixed to the engine of a large truck as indicated by aperture 107. When the clutch is engaged approximately 125 horsepower is used to drive the fan. The fan is a cooling fan which cools the engine under certain ambient conditions. When the vehicle is operating in a cold or cool environment the cooling of the engine may be sufficient by the ambient atmosphere and/or by the operating conditions of the vehicle. When the fan is needed or when there is no air pressure available, no air is supplied to the volume defined by reference numeral 111 and the friction plates of the clutch engage. When the fan is not needed air is then supplied to the volume 111 resulting in disengagement of the friction surfaces 109 and 110. Since the fan consumes 125 horsepower, it is desirable to operate it only when necessary thus making a clutch necessary.
FIG. 2 is a schematic of the prior art illustrating a solenoid 201 mounted on the fire wall 202 of a vehicle which vents the clutch. FIG. 2A is a schematic of the prior art illustrating a solenoid mounted on the fire wall of a vehicle which supplies air to the clutch. Referring to FIGS. 2 and 2A, reference numeral 200 is a schematic representation of the prior art three-way solenoid valve 201 mounted on fire wall 202, an air line 203 interconnecting solenoid valve 201 and journal 204, and a clutch 205. Journal 204 is shown mounted to the engine block 206. Solenoid valve 201 includes an air supply port labeled A and identified by reference numeral 207 and a vent port labeled B and identified by reference numeral 208. When air is vented from clutch 205, it must travel a considerable distance through the air line 203 and through the three-way solenoid valve 208. Solenoid valve 201 in FIG. 2 is shown deenergized which means if electrical power is lost, clutch 205 will be vented and the fan will be engaged. FIG. 2A illustrates the condition with the solenoid valve energized and air being supplied to the journal and into the clutch for disengaging the fan.
The prior art has the disadvantage of having a solenoid valve remotely mounted on the fire wall 202 with respect to the journal and the clutch. Therefore, in the prior art an air compressor must be interconnected by way of an air line to port 207 on solenoid valve 201. This solenoid valve mounted on the fire wall is then interconnected to the journal 204 mounted on the front of the engine block 206. Therefore, the prior art requires air tubing having at least four connections. An additional disadvantage of the prior art is the capacitance of the air line 203 as indicated in FIG. 2. By capacitance it is meant that air tubing 203 has a certain volume filled with compressed air which must be relieved before the clutch 205 may be engaged. As engine temperature sensors and measurements lag actual engine conditions, it is desirable to engage the fan relatively quickly so as to begin cooling the engine. Engagement and disengagement of the clutch is more accurately controlled with less air tubing volume. Less air tubing volume enables better control of the clutch with respect to time. The clutch can be engaged and disengaged when desired. In other words less air tubing volume optimizes control of the clutch which maximizes clutch engagement wear life.
Referring to FIG. 1, the principal vent is directly through coupling 114, seal 117 and passageway 106. Still referring to FIG. 1 the leak vent 118 is a passageway which extends through journal 101 and locking ring 119. Considerable machining must be performed to create leakage vent 118. The purpose of leakage vent 118 is to protect the bearings 116 from air which leaks between seal 117 and 114 and which flows into volume 120. Pumping air through bearings 116 would contribute to more rapid oxidation of the bearings and their components. Further, pumping air through the bearings will cause loss of lubricants.
A solenoid valve is mounted in the bore of a ferromagnetic journal which is used to complete the magnetic circuit when the coil is energized. Two flux flanges are employed which together with the plunger and ferromagnetic journal complete the magnetic circuit. The diameter of each of the flux flanges is the same. The flux flange diameter is slightly smaller than the diameter of the bore in the ferromagnetic journal. Typically, the air gap between the flanges and the inside bore of the journal is one to two thousandths of an inch so as to minimize the reluctance of the air gap and thus minimize the magnetomotive force and the size and amperage of the coil. A ferromagnetic material such as carbon steel which has high permeability is preferably used as the journal material.
The solenoid of the instant invention includes a leakage vent path and a principal vent path. The leakage vent begins with apertures in the locking flange of an extension affixed to an adapter which in turn is affixed to the second flange. Air is supplied to a coupling when the coil is energized and any leakage from that coupling is relieved through the apertures and notches of the flanges and finally through an aperture in the housing. The principal vent allows air supplied to the clutch to be evacuated therefrom permitting the clutch plates to engage driving a powerful engine cooling fan. Air from the clutch is evacuated through passageways and bores in the stop and out of a notch in the second flange.
First and second flux flanges made of ferromagnetic material such as steel are employed. Overmolding secures the flux flanges to the bobbin which has the current carrying coil wound therearound. An adapter at the outlet of the stop is also overmolded to the second flange. On the inlet side of the solenoid a plug is secured to the first flange by threaded engagement or by welding. The second flange includes a stop portion which has axial and transverse bores therein. Radially spaced axially extending passageways communicate air or other fluid through the stop.
When the coil is energized, the plunger moves from its first position to its second position. Radially spaced axially extending passageways reside on the periphery of the plunger such that communication therebetween with the passageways of the stop is established when the coil is energized. A plug having a valve seat forms the inlet to the solenoid valve. A first elastomeric insert in the plunger interengages the valve seat of the plug prohibiting flow when the coil is deenergized and the plunger is in the first position. When the coil is energized, the first elastomeric insert and plunger move away from the valve seat of the plug opening the passageway and permitting flow of air or other fluid into and through the solenoid valve. When the coil is energized, the plunger moves to its second position.
When the plunger moves to its second position the second elastomeric insert therein engages the stop prohibiting air flow into the axial bore of the stop. When the plunger is urged to its first position under the influence of a spring operable between the first flux flange and the plunger, flow of air or other fluid is permitted through the axial bore and transverse bore of the stop and out of a notch in the second flux flange. Two notches exist in each flange and are spaced 180xc2x0 from each other. The notches serve to aid the flow of air from the principal vent and from the leakage vent. The ferromagnetic journal is vented where the wires extend through the back side of the journal.
The journal mounted solenoid valve is used to control the supply of air to a clutch. When no air is supplied the clutch is engaged driving a 125 horsepower fan on a truck engine. When air is supplied to the clutch, the fan is disengaged. Bearings mounted on the ferromagnetic journal allow the rotation of a belt drive sheave. In the absence of air pressure of approximately 150 psig the belt driven sheave and clutch are rotated in unison. When the high power fan is disengaged, air is supplied to the clutch so as to separate the clutch from the sheave. When the clutch is engaged once again the air previously supplied to the clutch must be evacuated through the principal vent which includes passageways and bores in the stop. The leakage vent functions when air is supplied through the solenoid valve to the coupling. A non-rotating seal under the urging of a spring operating between a support and the seal engages a coupling which is rotating in unison with the sheave. If leakage of air occurs at the interface of the seal and the coupling then it must be evacuated. Leakage is evacuated through apertures in a locking flange, through notches in the flux flanges, through a small air gap between the flux flanges and the bore of the journal, and through an aperture in the bore to ambient atmosphere.
Accordingly, it is an object of the present invention to provide a solenoid valve mounted in a ferromagnetic journal and to use the ferromagnetic journal to complete the magnetic circuit.
It is a further object of the present invention to provide a second flux flange having an internal stop with radially spaced axially extending passageways therethrough and with axial and transverse bores.
It is a further object of the present invention to provide a second flux flange which includes a transverse bore.
It is a further object of the present invention to provide a plunger moveable between first and second positions and which includes passageways therethrough at the periphery thereof.
It is a further object of the present invention to provide a principal vent relieving pressure from a clutch and to provide a leakage vent for dissipating air which leaks from the seal-coupling interface when air is supplied to the clutch.
It is a further object of the present invention to provide a journal mounted solenoid valve for supplying air to a clutch.
It is a further object of the present invention to provide a solenoid valve which resides in the bore of a journal having a diameter of 1.25 inches.
These and other objects will be readily understood when reference is made to the Brief Description Of The Drawings, Description Of The Invention, and Claims which following hereinbelow.